Conventionally, there have been known web sites that are capable of providing information on transaction of transaction objects (e.g., purchase of items). In such web sites, for example, there is a function of automatically registering information on items purchased by a user as a purchase history, a function of registering information on items in a predetermined reference list by selecting a user's favorite (interested) items, or the like. Herein, the reference list is, for example, a list that holds a reference to information on transaction objects. As an example of a function of registering information in such a reference list, a favorite registration or a bookmark registration is known. This can allow a user to easily access the information on the transaction objects from the reference list.
Meanwhile, as the number of registrations of the transaction objects (e.g., the number of bookmark entries) is increased, there is a problem that it is difficult to search for and designate a web page a user wants to see. In order to solve this problem, Patent Literature 1 proposes a technique that can rearrange bookmark entries in order of reference time, based on reference date and time information.